They all work with proper placement, speed and bullet. I shoot a 6.5 Sherman SS with solid copper, 125 grain bullets at 3200'/sec and get exit wounds on moose at 500 yards. Never got that with my 7mm magnum and lead bullets. The copper bullets don't break up, so they penetrate much further and with a larger wound channel.
My father in law took a moose up in Alaska with a Savage 300 lever gun. 80 yards bang flop. 150 gr Cor-lokt. Don't think you need the latest and greatest, so any of those 30 cal. rifles you own will do. Unless you're looking at taking one past 1000 yrds.
Use some hunting skills to go with the shooting skills, 200yds or less. Going to have to walk to the kill either before after the shot. If I knew I was to have a good chance of getting a big moose, I would take my 375 RUM but for just walking around, a 35 Whelen will do it all. I am sure a 6.5 with the right bullet and high velocity will do the job, but I like big bullets. The woman in Canada killed a 12' Grizzley with a 22 LR, all is possible.
I have a Browning Safari in 300 WINMAG, Bought it at the Navy Exchange in the Philippines in 1967. Great and beautiful rifle. Too pretty to hunt with. Killed my first deer with it in 1975 near Mt. Baker in Washington State.